.container{
  width: 200px;
  height: 200px;
  background: pink;
  border-radius: 50%;
  box-shadow: 
  0 0 0 10px inset red,
  0 0 0 20px inset orange,
  0 0 0 30px inset yellow,
  0 0 0 40px inset lime,
  0 0 0 50px inset aqua,
  0 0 0 60px inset blue,
  0 0 0 70px inset magenta;

  clip-path: polygon(0 0, 100% 0, 100% 50%, 0% 50%);
}